Er Doped ZnO/SnS2/PEDOT:PSS Double Heterostructure Photodetector and Its Application as Optocoupler

This article presents an affordable ultraviolet (UV)-visible (VIS) Er-doped ZnO/tin sulphide/poly(3,4- ethylenedioxythiophene) polystyrene sulfonate (EZO/SnS2/ PEDOT:PSS based heterojunction photodetector (PD) fabricated on an indium tin oxide (ITO)-coated flexible polyethylene terephthalate (PET) substrate. The device shows responsivity ~26.02 A/W, detectivity ~4.8 Jones, and external quantum efficiency (EQE)
$\sim 7.6\times 104$
at an input power and voltage of
$0.018~\mu $
W
$^{-{1}}$
V, respectively. The suggested PD covers the UV to near-infrared (NIR) spectrums. The transient measurement gives a rise time (
${t} _{\text {r}}\text {)}$
of 0.61 ms and a fall time (
${t} _{\text {f}}\text {)}$
of 0.75 ms at 450 nm and −1 V bias. The proposed detector exhibits a self-powered response for visible regions. Furthermore, the application of the proposed detector is shown in an optocoupler circuit. In the designed optocoupler circuit, the proposed detector demonstrates a considerable current transfer ratio (CTR) (i.e., ~194).